Conflict handling of multiple dci

ABSTRACT

The present disclosure relates to a data transmitting device, data receiving device and the corresponding data transmitting method and data receiving method for transmitting/receiving data over a wireless channel in a communication system. In particular, a first resource grant is received for a data transmission in a subframe and a second resource grant for a data transmission of data in said subframe. Then, it is determined, according to which of the first resource grant and the second resource grant data are to be transmitted in the subframe; and the data is transmitted in the subframe according to the selected first grant or second grant.

BACKGROUND 1. Technical Field

The present disclosure relates to shared channel resource allocation andin particular to data receiving and transmitting apparatuses and methodsfor reception and transmission of data on a shared channel.

2. Description of the Related Art

Long Term Evolution (LTE)

Third-generation mobile systems (3G) based on WCDMA radio-accesstechnology are being deployed on a broad scale all around the world. Afirst step in enhancing or evolving this technology entails introducingHigh-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, alsoreferred to as High Speed Uplink Packet Access (HSUPA), giving a radioaccess technology that is highly competitive.

In order to be prepared for further increasing user demands and to becompetitive against new radio access technologies, 3GPP introduced a newmobile communication system which is called Long Term Evolution (LTE).LTE is designed to meet the carrier needs for high speed data and mediatransport as well as high capacity voice support for the next decade.The ability to provide high bit rates is a key measure for LTE.

The LTE system represents efficient packet-based radio access and radioaccess networks that provide full IP-based functionalities with lowlatency and low cost. In LTE, scalable multiple transmission bandwidthsare specified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in orderto achieve flexible system deployment using a given spectrum. In thedownlink, Orthogonal Frequency Division Multiplexing (OFDM)-based radioaccess was adopted because of its inherent immunity to multipathinterference (MPI) due to a low symbol rate, the use of a cyclic prefix(CP) and its affinity to different transmission bandwidth arrangements.Single-carrier frequency division multiple access (SC-FDMA)-based radioaccess was adopted in the uplink, since provisioning of wide areacoverage was prioritized over improvement in the peak data rateconsidering the restricted transmit power of the user equipment (UE).Many key packet radio access techniques are employed includingmultiple-input multiple-output (MIMO) channel transmission techniquesand a highly efficient control signaling structure is achieved in LTERel. 8/9.

LTE Architecture

The overall LTE architecture is shown in FIG. 1. The E-UTRAN consists ofan eNodeB, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) andcontrol plane (RRC) protocol terminations towards the user equipment(UE). The eNodeB (eNB) hosts the Physical (PHY), Medium Access Control(MAC), Radio Link Control (RLC) and Packet Data Control Protocol (PDCP)layers that include the functionality of user-plane header compressionand encryption. It also offers Radio Resource Control (RRC)functionality corresponding to the control plane. It performs manyfunctions including radio resource management, admission control,scheduling, enforcement of negotiated uplink Quality of Service (QoS),cell information broadcast, ciphering/deciphering of user and controlplane data, and compression/decompression of downlink/uplink user planepacket headers. The Radio Resource Control (RRC) layer controlscommunication between a UE and an eNB at the radio interface and themobility of a UE moving across several cells. The RRC protocol alsosupports the transfer of NAS information. For UEs in RRC_IDLE, RRCsupports notification from the network of incoming calls. RRC connectioncontrol covers all procedures related to the establishment, modificationand release of an RRC connection, including paging, measurementconfiguration and reporting, radio resource configuration, initialsecurity activation, and establishment of Signaling Radio Bearer (SRBs)and of radio bearers carrying user data (Data Radio Bearers, DRBs). TheeNodeBs are interconnected with each other by means of the X2 interface.

The eNodeBs are also connected by means of the S1 interface to the EPC(Evolved Packet Core), more specifically to the MME (Mobility ManagementEntity) by means of the S1-MME and to the Serving Gateway (SGW) by meansof the S1-U. The S1 interface supports a many-to-many relation betweenMMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user datapackets, while also acting as the mobility anchor for the user planeduring inter-eNodeB handovers and as the anchor for mobility between LTEand other 3GPP technologies (terminating S4 interface and relaying thetraffic between 2G/3G systems and PDN GW). For idle-state userequipment, the SGW terminates the downlink data path and triggers pagingwhen downlink data arrives for the user equipment. It manages and storesuser equipment contexts, e.g. parameters of the IP bearer service, ornetwork internal routing information. It also performs replication ofthe user traffic in case of lawful interception.

The MME is the key control-node for the LTE access-network. It isresponsible for idle-mode user equipment tracking and paging procedureincluding retransmissions. It is involved in the beareractivation/deactivation process and is also responsible for choosing theSGW for a user equipment at the initial attach and at the time ofintra-LTE handover involving Core Network (CN) node relocation. It isresponsible for authenticating the user (by interacting with the HSS).The Non-Access Stratum (NAS) signaling terminates at the MME, and it isalso responsible for the generation and allocation of temporaryidentities to user equipment. It checks the authorization of the userequipment to camp on the service provider's Public Land Mobile Network(PLMN) and enforces user equipment roaming restrictions. The MME is thetermination point in the network for ciphering/integrity protection forNAS signaling and handles the security key management. Lawfulinterception of signaling is also supported by the MME. The MME alsoprovides the control plane function for mobility between LTE and 2G/3Gaccess networks with the S3 interface terminating at the MME from theSGSN. The MME also terminates the S6a interface towards the home HSS forroaming user equipment.

Component Carrier Structure in LTE

The downlink component carrier of a 3GPP LTE system is subdivided in thetime-frequency domain in so-called subframes. In 3GPP LTE each subframeis divided into two downlink slots as shown in FIG. 2, wherein the firstdownlink slot comprises the control channel region (PDCCH region) withinthe first OFDM symbols. Each subframe consists of a give number of OFDMsymbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release8)), wherein each OFDM symbol spans over the entire bandwidth of thecomponent carrier. The OFDM symbols thus each consist of a number ofmodulation symbols transmitted on respective subcarriers. In LTE, thetransmitted signal in each slot is described by a resource grid ofN^(DL) _(RB)×N^(RB) _(SC) subcarriers and N^(DL) _(symb) OFDM symbols.N^(DL) _(RB) is the number of resource blocks within the bandwidth. Thequantity N^(DL) _(RB) depends on the downlink transmission bandwidthconfigured in the cell and shall fulfill

N_(RB) ^(min,DL)≤N_(RB) ^(DL)≤N_(RB) ^(max,DL),

where N^(min,DL) _(RB)=6 and N^(max,DL) _(RB)=110 are respectively thesmallest and the largest downlink bandwidths, supported by the currentversion of the specification. N^(RB) _(SC) is the number of subcarrierswithin one resource block. For normal cyclic prefix subframe structure,N^(RB) _(SC)=12 and N^(DL) _(symb)=7. For the uplink, a grid shown inFIG. 2 is provided; reference is also made in this respect to FIGS.6.2.2-1 and 5.2.1-1 in 3GPP TS 36.211, v. 13.2.0.

Assuming a multi-carrier communication system, e.g. employing OFDM, asfor example used in 3GPP Long Term Evolution (LTE), the smallest unit ofresources that can be assigned by the scheduler is one “resource block”.A physical resource block (PRB) is defined as consecutive OFDM symbolsin the time domain (e.g. 7 OFDM symbols) and consecutive subcarriers inthe frequency domain as exemplified in FIG. 2 (e.g. 12 subcarriers for acomponent carrier). In 3GPP LTE (Release 8), a physical resource blockthus consists of resource elements, corresponding to one slot in thetime domain and 180 kHz in the frequency domain (for further details onthe downlink resource grid, see for example 3GPP TS 36.211, “EvolvedUniversal Terrestrial Radio Access (E-UTRA); Physical Channels andModulation (Release 8)”, section 6.2, (for instance version v8.9.0,available at http://www.3gpp.org).

One subframe consists of two slots, so that there are 14 OFDM symbols ina subframe when a so-called “normal” CP (cyclic prefix) is used, and 12OFDM symbols in a subframe when a so-called “extended” CP is used. Forsake of terminology, in the following the time-frequency resourcesequivalent to the same consecutive subcarriers spanning a full subframeis called a “resource block pair”, or equivalent “RB pair” or “PRBpair”.

The term “component carrier” refers to a combination of several resourceblocks in the frequency domain. In future releases of LTE, the term“component carrier” is no longer used; instead, the terminology ischanged to “cell”, which refers to a combination of downlink andoptionally uplink resources. The linking between the carrier frequencyof the downlink resources and the carrier frequency of the uplinkresources is indicated in the system information transmitted on thedownlink resources.

Similar assumptions for the component carrier structure will apply tolater releases too.

Carrier Aggregation in LTE-A for Support of Wider Bandwidth

The bandwidth that the LTE-Advanced system is able to support is 100MHz, while an LTE system can only support 20 MHz. In carrieraggregation, two or more component carriers are aggregated in order tosupport wider transmission bandwidths up to 100 MHz. Several cells inthe LTE system are aggregated into one wider channel in the LTE-Advancedsystem which is wide enough for 100 MHz even though these cells in LTEmay be in different frequency bands. A user equipment may simultaneouslyreceive or transmit on one or multiple component carriers (correspondingto multiple serving cells) depending on its capabilities. Carrieraggregation is supported for both contiguous and non-contiguouscomponent carriers with each component carrier limited to a maximum of110 Resource Blocks in the frequency domain (using the 3GPP LTE (Release8/9) numerology).

When carrier aggregation is configured, the mobile terminal only has oneRRC connection with the network. At RRC connectionestablishment/re-establishment, one cell provides the security input(one ECGI, one PCI and one ARFCN) and the non-access stratum mobilityinformation (e.g. TAI) similarly as in LTE Rel. 8/9. After RRCconnection establishment/re-establishment, the component carriercorresponding to that cell is referred to as the downlink Primary Cell(PCell). There is always one and only one downlink PCell (DL PCell) andone uplink PCell (UL PCell) configured per user equipment in connectedstate. Within the configured set of component carriers, other cells arereferred to as Secondary Cells (SCells); with carriers of the SCellbeing the Downlink Secondary Component Carrier (DL SCC) and UplinkSecondary Component Carrier (UL SCC). Maximum five serving cells,including the PCell, can be configured for one UE.

Uplink Access scheme for LTE

For uplink transmission, power-efficient user-terminal transmission isnecessary to maximize coverage. Single-carrier transmission combinedwith FDMA with dynamic bandwidth allocation has been chosen as theevolved UTRA uplink transmission scheme. The main reason for thepreference for single-carrier transmission is the lower peak-to-averagepower ratio (PAPR), compared to multi-carrier signals (OFDMA), and thecorresponding improved power-amplifier efficiency and improved coverage(higher data rates for a given terminal peak power). During each timeinterval, eNode B assigns users a unique time/frequency resource fortransmitting user data, thereby ensuring intra-cell orthogonality. Anorthogonal access in the uplink promises increased spectral efficiencyby eliminating intra-cell interference. Interference due to multipathpropagation is handled at the base station (eNode B), aided by insertionof a cyclic prefix in the transmitted signal.

The basic physical resource used for data transmission consists of afrequency resource of size BWgrant during one time interval, e.g. asubframe, onto which coded information bits are mapped. It should benoted that a subframe, also referred to as transmission time interval(TTI), is the smallest time interval for user data transmission. It ishowever possible to assign a frequency resource BWgrant over a longertime period than one TTI to a user by concatenation of subframes.

Layer 1/Layer 2 Control Signaling

In order to inform the scheduled users about their allocation status,transport format and other transmission-related information (e.g. HARQinformation, transmit power control (TPC) commands), L1 /L2 controlsignaling is transmitted on the downlink along with the data. L1/L2control signaling is multiplexed with the downlink data in a subframe,assuming that the user allocation can change from subframe to subframe.It should be noted that user allocation might also be performed on a TTI(Transmission Time Interval) basis, where the TTI length can be amultiple of the subframes. The TTI length may be fixed in a service areafor all users, may be different for different users, or may even bydynamic for each user. Generally, the L1/2 control signaling needs onlybe transmitted once per TTI. Without loss of generality, the followingassumes that a TTI is equivalent to one subframe.

The L1/L2 control signaling is transmitted on the Physical DownlinkControl Channel (PDCCH). A PDCCH carries a message as a Downlink ControlInformation (DCI), which in most cases includes resource assignments andother control information for a mobile terminal or groups of UEs. Ingeneral, several PDCCHs can be transmitted in one subframe.

It should be noted that in 3GPP LTE, assignments for uplink datatransmissions, also referred to as uplink scheduling grants or uplinkresource assignments, are also transmitted on the PDCCH. Furthermore,Release 11 introduced an EPDCCH that fulfills basically the samefunction as the PDCCH, i.e. conveys L1/L2 control signaling, even thoughthe detailed transmission methods are different from the PDCCH. Furtherdetails can be found particularly in the current versions of 3GPP TS36.211 (e.g. version v13.2.0) and 3GPP TS 36.213, “Physical LayerProcedures”, v13.2.0, available free of charge at www.3gpp.org.Consequently, most items outlined in the background and the embodimentsapply to PDCCH as well as EPDCCH, or other means of conveying L1/L2control signals, unless specifically noted.

Generally, the information sent in the L1/L2 control signaling forassigning uplink or downlink radio resources (particularly LTE(-A)Release 10) can be categorized to the following items:

-   -   User identity, indicating the user that is allocated. This is        typically included in the checksum by masking the CRC with the        user identity;    -   Resource allocation information, indicating the resources (e.g.        Resource Blocks, RBs) on which a user is allocated. This        information is also termed resource block assignment (RBA).        Note, that the number of RBs on which a user is allocated can be        dynamic;    -   Carrier indicator, which is used if a control channel        transmitted on a first carrier assigns resources that concern a        second carrier, i.e. resources on a second carrier or resources        related to a second carrier; (cross carrier scheduling);    -   Modulation and coding scheme that determines the employed        modulation scheme and coding rate;    -   HARQ information, such as a new data indicator (NDI) and/or a        redundancy version (RV) that is particularly useful in        retransmissions of data packets or parts thereof;    -   Power control commands to adjust the transmit power of the        assigned uplink data or control information transmission;    -   Reference signal information such as the applied cyclic shift        and/or orthogonal cover code index, which are to be employed for        transmission or reception of reference signals related to the        assignment;    -   Uplink or downlink assignment index that is used to identify an        order of assignments, which is particularly useful in TDD        systems;    -   Hopping information, e.g. an indication whether and how to apply        resource hopping in order to increase the frequency diversity;    -   CSI request, which is used to trigger the transmission of        channel state information in an assigned resource; and    -   Multi-duster information, which is a flag used to indicate and        control whether the transmission occurs in a single cluster        (contiguous set of RBs) or in multiple clusters (at least two        non-contiguous sets of contiguous RBs). Multi-cluster allocation        has been introduced by 3GPP LTE-(A) Release 10.

It is to be noted that the above listing is non-exhaustive, and not allmentioned information items need to be present in each PDCCHtransmission depending on the DCI format that is used.

In the current LTE specification (Rel-13), the modulation and codingscheme (MCS) is determined by the parameters modulation order, transportblock size (TBS) and number of resource elements (REs) that are used forthe transport block transmission.

Supported modulation orders (number of bits per modulation symbol) forLTE in licensed bands comprise 2, 4, 6 and 8; corresponding to QPSK,16QAM, 64QAM and 256QAM, respectively. Whether all of them will besupported for unlicensed band operation as well has not been discussedso far, but it is advantageous if the same set of modulation order willbe supported for unlicensed band operation as well.

The TBS is determined by the TBS index by means of the MCS index that isindicated to the UE within the DCI and the number of PRBs that areallocated for the PDSCH transmission as described in Section 7.1.7 of3GPP TS 36.213, v13.2.0, titled “Evolved Universal Terrestrial RadioAccess (E-UTRA); Physical layer procedures”, available at www.3gpp.org.The LTE specification TS 36.213 contains two-dimensional TBS tables inSection 7.1.7.2 of which the TBS index and number of scheduled PBRsindicates row and column, respectively. The table specifies thetransport block sizes and thus, the coding and puncturing applicable.

FIG. 5 shows an uplink MCS table which assigns each of the 32 values0-31 an MCS and/or a redundancy version. In particular, the first columnrepresents an MCS index, which is included in the DCI. Each MCS index0-28 is associated with a particular combination a of the modulationorder (2=QPSK, 4=16QAM, 6=64QAM) and the Transport Block Size (TBS)Index as well as redundancy version index. The MCS indices (values)29-31 are not associated with a particular modulation (order) or codingscheme (TBS index) in the uplink, but rather define the redundancyversions 1-3, while it is assumed that the modulation and coding schemeremains as it was in a preceding transmission (e.g. with redundancyversion 0) of the same transport block,

A Redundancy Version (RV) specifies a starting point in a circular(re)transmission buffer to start reading operation. Usually RV=0 isselected for the initial transmission to send mainly systematic bits,since this approach has shown a good compromise between successfuldecoding at high Signal-to-Noise ratios (SNRs) and at low SNRs. Thescheduler can choose different RVs on transmissions of the same packetto support both incremental redundancy and Chase combining. There arefour redundancy versions currently defined, characterized by theirstarting positions, and numbered from 0 to 3. The usual sequence ofthese RVs for the first transmission and the subsequent retransmissionis 0, 2, 3, 1.

Downlink control information occurs in several formats that differ inoverall size and also in the information contained in their fields asmentioned above. The different DCI formats that are currently definedfor LTE are as follows and described in detail in 3GPP TS 36.212,“Multiplexing and channel coding”, section 5.3.3.1 (current versionv13.2.0, available at http://www.3gpp.org). In addition, for furtherinformation regarding the DCI formats and the particular informationthat is transmitted in the DCI, please refer to the mentioned technicalstandard or to LTE—The UMTS Long Term Evolution—From Theory to Practice,Edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Chapter 9.3.

-   -   Format 0: DCI format 0 is used for the transmission of resource        grants for the PUSCH, using single-antenna port transmissions in        uplink transmission mode 1 or 2,    -   Format 1: DCI format 1 is used for the transmission of resource        assignments for single codeword PDSCH transmissions (downlink        transmission modes 1, 2 and 7).    -   Format 1A: DCI format 1A is used for compact signaling of        resource assignments for single codeword PDSCH transmissions,        and for allocating a dedicated preamble signature to a mobile        terminal for contention-free random access (for all        transmissions modes).    -   Format 1B: DCI format 1B is used for compact signaling of        resource assignments for PDSCH transmissions using closed loop        preceding with rank-1 transmission (downlink transmission mode        6). The information transmitted is the same as in Format 1A, but        with the addition of an indicator of the precoding vector        applied for the PDSCH transmission.    -   Format 10: DCI format 1C is used for very compact transmission        of PDSCH assignments. When format 1C is used, the PDSCH        transmission is constrained to using QPSK modulation. This is        used, for example, for signaling paging messages and broadcast        system information messages.    -   Format 1D: DCI format 1D is used for compact signaling of        resource assignments for PDSCH transmission using multi-user        MIMO. The information transmitted is the same as in Format 1B,        but instead of one of the bits of the precoding vector        indicators, there is a single bit to indicate whether a power        offset is applied to the data symbols. This feature is needed to        show whether or not the transmission power is shared between two        UEs. Future versions of LTE may extend this to the case of power        sharing between larger numbers of UEs.    -   Format 2: DCI format 2 is used for the transmission of resource        assignments for PDSCH for closed-loop MIMO operation        (transmission mode 4).    -   Format 2A: DCI format 2A is used for the transmission of        resource assignments for PDSCH for open-loop MIMO operation. The        information transmitted is the same as for Format 2, except that        if the eNodeB has two transmit antenna ports, there is no        precoding information, and for four antenna ports two bits are        used to indicate the transmission rank (transmission mode 3).    -   Format 2B: Introduced in Release 9 and is used for the        transmission of resource assignments for PDSCH for dual-layer        beamforming (transmission mode 8).    -   Format 2C: Introduced in Release 10 and is used for the        transmission of resource assignments for PDSCH for closed-loop        single-user or multi-user MIMO operation with up to 8 layers        (transmission mode 9).    -   Format 2D: Introduced in Release 11 and used for up to 8 layer        transmissions; mainly used for COMP (Cooperative Multipoint)        (transmission mode 10)    -   Format 3 and 3A: DCI formats 3 and 3A are used for the        transmission of power control commands for PUCCH and PUSCH with        2-bit or 1-bit power adjustments respectively. These DCI formats        contain individual power control commands for a group of UEs.    -   Format 4: DCI format 4 is used for the scheduling of the PUSCH,        using closed-loop spatial multiplexing transmissions in uplink        transmission mode 2.

The PDCCH carries DCI on an aggregation of one or a plurality ofconsecutive control channel elements (CCEs). A control channel elementcorresponds to 9 resource element groups (REG) of which each consists offour or six resource elements.

A search space indicates a set of CCE locations where the UE may findits PDCCHs. Each PDCCH carries one DCI and is identified by the RNTI(radio network temporary identity) implicitly encoded in the CRCattachment of the DCI. The UE monitors the CCEs of a configured searchspace(s) by blind decoding and checking the CRC.

A search space may be a common search space and a UE-specific searchspace. A UE is required to monitor both common and UE-specific searchspaces, which may be overlapping. The common search space carries theDCIs that are common for all UEs such as system information (using theSI-RNTI), paging (P-RNTI), PRACH responses (RA-RNTI), or UL TPC commands(TPC-PUCCH/PUSCH-RNTI). The UE-specific search space can carry DCIs forUE-specific allocations using the UE's assigned C-RNTI, semi-persistentscheduling (SPS C-RNTI), or initial allocation (temporary C-RNTI).

While traditional wireless communications (Single-Input Single-Output(SISO)) exploit time- or frequency-domain pre-processing and decoding ofthe transmitted and received data respectively, the use of additionalantenna elements at either the base station (eNodeB) or User Equipment(UE) side (on the downlink or uplink) opens an extra spatial dimensionto signal preceding and detection. Space-time processing methods exploitthis dimension with the aim of improving the link's performance in termsof one or more possible metrics, such as the error rate, communicationdata rate, coverage area and spectral efficiency (expressed inbps/Hz/cell). Depending on the availability of multiple antennas at thetransmitter and/or the receiver, such techniques are classified asSingle-Input Multiple-Output (SIMM), Multiple-Input Single-Output (MISO)or MIMO. While a point-to-point multiple-antenna link between a basestation and one UE is referred to as Single-User MIMO (SU-MIMO),Multi-User MIMO (MU-MIMO) features several UEs communicatingsimultaneously with a common base station using the same frequency- andtime-domain resources.

The LTE standard defines what is known as antenna ports (cf. TS 36.211,v13.2.0, Section 5.2.1). The antenna ports do not correspond to physicalantennas, but rather are logical entities distinguished by theirreference signal sequences. Multiple antenna port signals can betransmitted on a single transmit antenna. Correspondingly, a singleantenna port can be spread across multiple transmit antennas.

A spatial layer is the term used in LTE for one of the different streamsgenerated by spatial multiplexing. A layer can be described as a mappingof symbols onto the transmit antenna ports. Each layer is identified bya preceding vector of size equal to the number of transmit antenna portsand can be associated with a radiation pattern. The rank of thetransmission is the number of layers transmitted.

A codeword is an independently encoded data block, corresponding to asingle Transport Block (TB) delivered from the Medium Access Control(MAC) layer in the transmitter to the physical layer, and protected witha CRC. For ranks greater than 1, two codewords can be transmitted. Thenumber of codewords is always less than or equal to the number oflayers, which in turn is always less than or equal to the number ofantenna ports. It is possible to map Transport Block 1 to Codeword 0 andTransport Block 2 to Codeword 1, or alternatively to map Transport Block2 to Codeword 0 and Transport Block 1 to Codeword 1.

In order to enable fast rank and precoder adaptation for a downlinktransmission mode, it is possible to configure the UE to feed back aRank Indicator (RI) together with a Precoding Matrix Indicator (PMI)which indicate the preferred RI/PMI based on the measured quality. Onthe other hand, the eNB indicates via a Transmitted Precoding MatrixIndicator (TPMI) in the downlink assignment message on the PDCCH whetherit is applying the UE's preferred precoder, and if not, which precoderis used. This enables the UE to derive the correct phase referencerelative to the cell-specific RSs in order to demodulate the PDSCH data.

Similarly, the eNB is able to control the rank and precoder for anuplink transmission mode. In contrast to downlink, there is no explicitfeedback by the UE such as RI and PMI. The eNB rather can take thetransmitted reference symbols from an uplink transmission (such as thedemodulation reference symbols or sounding reference symbols) and usethese to determine an appropriate number of transmitted layers and TPMI,which is then indicated in the uplink resource assignment message (DCI)transmitted on a control channel such as the PDCCH.

LTE on Unlicensed Bands—Licensed-Assisted Access LAA

A work item addressing the specification of LTE for unlicensed bandoperation was initiated in June 2015. The reason for extending LTE tounlicensed bands is the ever-growing demand for wireless broadband datain conjunction with the limited amount of licensed bands. Unlicensedspectrum therefore is more and more considered by cellular operators asa complementary tool augment their service offering. The advantage ofLTE in unlicensed bands compared to relying on other radio accesstechnologies (RAT) such as Wi-Fi is that complementing the LTE platformwith unlicensed spectrum access enables operators and vendors toleverage the existing or planned investments in LTE/EPC hardware in theradio and core network.

However, it has to be taken into account that unlicensed spectrum accesscan never match the qualities of licensed spectrum due to the inevitablecoexistence with other radio access technologies (RATs) in theunlicensed spectrum. LTE operation in unlicensed bands will therefore atleast in the beginning be considered rather a complement to LTE onlicensed spectrum than stand-alone operation in unlicensed spectrum.Based on this assumption, 3GPP established the term Licensed AssistedAccess (LAA) for the LTE operation in unlicensed bands in conjunctionwith at least one licensed band. Future stand-alone operation of LTE inunlicensed spectrum without relying on LAA is however not excluded.

The current general LAA approach at 3GPP is to make use of the alreadyspecified Rel-12 carrier aggregation (CA) framework as much as possiblewhere the CA framework configuration comprises a so-called primary cell(PCell) carrier and one or more secondary cell (SCell) carriers. CAsupports in general both self-scheduling of cells (schedulinginformation and user data are transmitted on the same carrier) andcross-carrier scheduling between cells (scheduling information in termsof PDCCH/EPDCCH and user data in terms of PDSCH/PUSCH are transmitted ondifferent carriers).

The basic envisioned approach at 3GPP is that the PCell will be operatedon a licensed band while one or more SCells will be operated inunlicensed bands. The benefit of this strategy is that the PCell can beused for reliable transmission of control messages and user data withhigh quality of service (QoS) demands, such as for example voice andvideo, while a PCell in unlicensed spectrum might yield, depending onthe scenario, to some extent significant QoS reduction due to inevitablecoexistence with other RATs. A very basic scenario is illustrated inFIG. 3, with a licensed PCell, licensed SCell 1, and various unlicensedSCells 2, 3, and 4 (exemplarily depicted as small cells). Thetransmission/reception network nodes of unlicensed SCells 2, 3, and 4could be remote radio heads managed by the eNB or could be nodes thatare attached to the network but not managed by the eNB. For simplicity,the connection of these nodes to the eNB or to the network is notexplicitly shown in the drawing.

It has been agreed at 3GPP, that the LAA investigation and specificationwill focus in the first step on unlicensed bands at 5 GHz. One of themost critical issues is therefore the coexistence with Wi-Fi (IEEE802.11) systems operating in these unlicensed bands. In order to supportfair coexistence between LTE and other technologies such as Wi-Fi aswell as fairness between different LTE operators in the same unlicensedband, the channel access procedures of LTE for unlicensed band operationhas to abide by certain sets of regulatory rules which depend on region(Europe, US, China, Japan, etc.) and considered frequency band. Acomprehensive description of the regulatory requirements for operationin unlicensed bands at 5 GHz is given in 3GPP TR 36.889, v13.0.0 of June2015, titled “Study on Licensed-Assisted Access to Unlicensed Spectrum”,available at www.3gpp.org. Depending on region and band, regulatoryrequirements that have to be taken into account when designing LAAprocedures comprise Dynamic Frequency Selection (DFS), Transmit PowerControl (TPC), Listen Before Talk (LBT) and discontinuous transmissionwith limited maximum transmission duration. The intention of 3GPP is totarget a single global framework for LAA which basically means that allrequirements for different regions and bands at 5 GHz have to be takeninto account for the system design.

The DFS operation and corresponding requirements are associated with amaster-slave principle. The master shall detect radar interference, canhowever rely on another device, that is associated with the master, toimplement the radar detection. Following the European regulationregarding LBT, devices have to perform a Clear Channel Assessment (CCA)before occupying the radio channel. It is only allowed to initiate atransmission on the unlicensed channel after detecting the channel asfree based on energy detection. The equipment has to observe the channelfor a certain minimum during the CCA. The channel is considered occupiedif the detected energy level exceeds a configured CCA threshold. If thechannel is classified as free, the equipment is allowed to transmitimmediately. The maximum transmit duration is thereby restricted inorder to facilitate fair resource sharing with other devices operatingon the same band.

The energy detection for the CCA is performed over the whole channelbandwidth (e.g. 20 MHz in unlicensed bands at 5 GHz), which means thatthe reception power levels of all subcarriers of an LTE OFDM symbolwithin that channel contribute to the evaluated energy level at thedevice that performed the CCA.

Furthermore, the total time during which an equipment occupies a givenunlicensed channel by means of continuous transmission withoutre-evaluating the availability of that channel (i.e. LBT/CCA) is definedas the Channel Occupancy Time (see ETSI 301 893, under clause 4.8.3.1).The Channel Occupancy Time shall be in the range of 1 ms to 10 ms, wherethe maximum Channel Occupancy Time could be e.g. 4 ms as currentlydefined for Japan. There is furthermore a minimum Idle time during whichthe equipment is not allowed to occupy the unlicensed channel againafter a transmission on that unlicensed channel, the minimum Idle timebeing at least 5% of the preceding Channel Occupancy Time. At the end ofthe Idle Period, the UE can perform a new CCA, and so on. Thistransmission behavior is schematically illustrated in FIG. 4.

Multiple Subframe Allocation

There has been a discussion in 3GPP RANI concerning the possibility ofmulti-subframe scheduling for the uplink LAA (cf. 3GPP RANI contributionR1-160557 titled “Discussion on multi-subframe scheduling for UL LAA”,Meeting #84 in Malta, February 2016). Accordingly, with the exception ofsemi-persistent scheduling (SPS) and UL grants in TDD UL/DLconfiguration 0, only per-TTI scheduling is allowed. Downlink or uplinkgrant received in subframe n schedules only one PDSCH or PUSCH for asubframe n+k, where k=0 and 4 for downlink and uplink respectively, inFDD case.

Based on FDD HARQ timing, upon reception of the UL grant in subframe n,the scheduled LAA UE(s) would require to perform LBT on the scheduledunlicensed carrier to occupy the channel before the start of PUSCHtransmission in the subframe n+4. The eNB cannot predict LBT result atUE side when the UL grant is sent in subframe n, the eNB has no choicebut to send the UL grant with the expectation that UEs would occupy thechannel for the scheduled PUSCH in subframe n+4. However, if UE cannotcomplete the required LBT for uplink transmission on time, the scheduledPUSCH cannot be transmitted in the scheduled subframe, which results innot only the waste resources for UL grants but also the waste ULresource for PUSCH transmission. LAA UL transmission should be designedto increase channel access opportunity of LAA with less schedulingoverhead.

To increase channel access opportunity while minimizing signalingoverhead to schedule PUSCH on unlicensed carrier, multi-subframescheduling is provided. A multi-subframe scheduling allows UE totransmit PUSCH in one or multiple subframes in the scheduled subframeswhenever UEs pass the LBT by one UL grant. In case of demands on DL islow but that for UL is high, it is beneficial to support multi-subframescheduling to avoid unnecessary DL transmission to send UL grant. Inthis case, it would not only save the signaling overhead for sending ULgrant but also reduce the overall unlicensed channel occupancy time,which is beneficial for a fair coexistence with other unlicensed carriercommunication nodes or systems.

For uplink transmissions on an unlicensed carrier, the eNB has thechoice between up to four DCI formats 0A/0B/4A/4B, where in additioneach of these can constitute a single-stage grant or a triggered(=two-stage) grant.

Each of the DCI formats contains a ‘scheduling delay’ field thatindicates an additional scheduling offset between 0 and 15 subframes incase of single-stage grants, and for triggered grants between 0 and 3subframes in the first stage DCI of a triggered grant with an additionaloffset of {1;2;3;4;6} subframes indicated by the second stage of atriggered grant—resulting in an additional scheduling offset between 0and 9 subframes after the reception of the second stage of a triggeredgrant.

Regardless whether resources are granted by means of a single-stagegrant or a triggered grant, the ability to indicate one out of aplurality of scheduling offsets in any of these grants implies that DCItransmitted in different subframes n1 and n2 are able to schedule PUSCHtransmissions in the same uplink subframe nu. The current specificationdoes not specify any UE behavior for such a conflict of grantedresources.

SUMMARY

If the UE behavior is unspecified, this may cause misalignments betweenthe eNB and the UE and thus lead to delays and resource wasting.

One non-limiting and exemplary embodiment provides an approach improvingthe resource usage in connection with transmission or reception grantsignaling.

This is achieved by the features of the independent claims.

Advantageous embodiments are subject matter of the dependent claims.

In an embodiment, the techniques disclosed here feature datatransmitting device that is provided for transmitting data to a datareceiving node over a wireless channel in a communication system, thedata transmitting device comprising: grant receiving circuitry forreceiving a first resource grant for a data transmission in a subframeand a second resource grant for a data transmission of data in saidsubframe; and transmission control circuitry for selecting according towhich of the first resource grant and the second resource grant data areto be transmitted in the subframe; and a transmitter for transmittingthe data in the subframe according to the selected first grant or secondgrant.

It should be noted that general or specific embodiments may beimplemented as a signal, a system, a method, an integrated circuit, acomputer program, a storage medium, or any selective combinationthereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following exemplary embodiments are described in more detail withreference to the attached figures and drawings.

FIG. 1 shows an exemplary architecture of a 3GPP LTE system;

FIG. 2 shows an exemplary downlink resource grid of a downlink slot of asubframe as defined for 3GPP LTE (Release 8/9);

FIG. 3 illustrates an exemplary licensed-assisted access scenario, withvarious licensed and unlicensed cells;

FIG. 4 illustrates schematically the transmission timing on anunlicensed band, including the different periods, Channel OccupancyTime, Idle Period, and Fixed Frame Period;

FIG. 5 is a schematic drawing illustrating UE handling based onpreference for SSF grant for the conflicting subframe and using the MSFgrant otherwise;

FIG. 6 is a schematic drawing illustrating UE handling based onpreference for SSF grant for the conflicting subframe;

FIG. 7 is a schematic drawing illustrating UE handling based onselection of the most recent grant but allowing transmission accordingto an earlier MSF for subframes without grant conflicting;

FIG. 8 is a schematic drawing illustrating UE handling based onselection of the most recent grant;

FIG. 9 is a schematic drawing illustrating UE handling when only in thesubframe for which different grants were received, no transmission takesplace;

FIG. 10 is a schematic drawing illustrating UE handling when only in thesubframe for which different grants were received, no transmission takesplace;

FIG. 11 is a block diagram illustrating apparatuses for handlingsituations in which for one subframes more than one different grants arereceived; and

FIG. 12 is a block diagram illustrating methods for handling situationsin which for one subframes more than one different grants are received.

DETAILED DESCRIPTION

A mobile station or mobile node or user terminal or user equipment is aphysical entity within a communication network. One node may haveseveral functional entities. A functional entity refers to a software orhardware module that implements and/or offers a predetermined set offunctions to other functional entities of a node or the network. Nodesmay have one or more interfaces that attach the node to a communicationfacility or medium over which nodes can communicate. Similarly, anetwork entity may have a logical interface attaching the functionalentity to a communication facility or medium over which it maycommunicate with other functional entities or correspondent nodes.

The term “radio resources” as used in the set of claims and in theapplication is to be broadly understood as referring to physical radioresources, such as time-frequency resources and/or space or coderesources.

The term “unlicensed cell” or alternatively “unlicensed carrier” as usedin the set of claims and in the application is to be understood broadlyas a cell/carrier in an unlicensed frequency band. Correspondingly, theterm “licensed cell” or alternatively “licensed carrier” as used in theset of claims and in the application is to be understood broadly as acell/carrier in a licensed frequency band. Exemplarily, these terms areto be understood in the context of 3GPP as of Release 12/13 and theLicensed-Assisted Access Work Item.

A transport block (TB) that will be transmitted in a physical downlinkshared channel (PDSCH) or physical uplink shared channel (PUSCH) has tobe prepared prior to the transmission of the PDSCH or PUSCH itself. Acertain number of bits, given by the transport block size (TBS), aretaken from a specific HARQ process queue of the MAC layer and passeddown to the PHY (physical layer) together with a corresponding MACheader.

As explained above, a single uplink transmission grant may allocateresources either in a single-subframe or in multiple subframes. In LTE,DCI format 0A is for allocating resources in a single subframe and for asingle antenna port while DCI format 0B allocates resources in one ormultiple subframes for a single antenna port. For multiple antenna ports(MIMO, SISO), DCI format 4A reserves a single subframe, whereas DCIformat 4B reserves one or multiple subframes.

In particular, currently in 3GPP it is agreed that DCI format 0B/4Bindicates the number of scheduled subframes, HARQ process IDs for thescheduled subframes by indicating HARQ process ID for the firstscheduled subframe, and HARQ process IDs for other subframes are derivedtherefrom by a given rule. In particular, the HARQ process IDs for othersubframes are consecutive with the indicated HARQ process IDs, modulothe maximum number of HARQ processes. The DCI format 0B/4B furtherindicates RVs for the scheduled subframes by indicating a 1-bit RV valueper scheduled subframe (regardless of the number of scheduled transportblocks in each subframe), and can indicate RV 0 or 2.

Each of these four DCI formats may also include a field for indicating ascheduling delay. The scheduling delay specifies by how many subframesthe transmission scheduled by the same DCI is to be postponed. In theLTE, as described in the background section the scheduling delay fieldenables signaling of up to 16 delay values. These values specify offsetwith respect to a predefined minimum number of subframes. In particular,in LTE up to Release 13, the transmission scheduled by a DCI occursalways at least four subframes after reception of said DCI. Thisprovides for processing time to the transmitting node which is in uplinkthe UE. For instance, when a DCI is received in a subframe n, thenscheduling delay values 0 to 15 specify that the transmission is to takeplace in one of the respective subframes n+4 to n+19. Thus, thetransmission may be postponed by up to 15 additional subframes. Ingeneral, for the advanced systems after LTE such as NR, thepredetermined delay may be lower than 4 or even zero so that thescheduling delay may directly indicate the offset between reception ofthe grant and the data transmission.

Employment of the scheduling delay is one of reasons that the schedulingnode may transmit different grants for the same subframe resource. Forinstance, a grant with a scheduling delay may be transmitted at firstand later another grant for the same subframe may be transmitted with asmaller or no scheduling delay. Such situations may be advantageous forthe scheduling node for instance if it is erroneously believed that thefirst grant has not been received. However, such behavior may also beadvantageous in other situations such as scheduling for multiplesubframes.

In general, the following conflicts between different grants for thesame subframe may occur in an uplink subframe nu:

-   -   A single subframe (SSF) grant is transmitted in a subframe n1        and another SSF grant is transmitted in subframe n2.    -   A SSF grant is transmitted in subframe n1 and a multiple        subframe (MSF) grant is transmitted in subframe n2.    -   An MSF grant transmitted in subframe n1 and an SSF grant is        transmitted in subframe n2.    -   An MSF grant is transmitted in subframe n1 and another MSF grant        is transmitted in subframe n2.

In the context of LTE, n1 differs from n2 and this will also be the casefor other systems with a shared channel. However, in general, n1 equalto n2 could also occur especially if there are multiple schedulingentities or grants transmitted on different resources at the same time.

Current LTE system does not specify the terminal behavior in uplink uponreception of two different grants for subframe nu. Thus, it is unclear,how the terminal is to react in subframe nu and nu+1 etc.

Without loss of generality, we assume that there is a difference in atleast one transmission-related parameter indicated by the DCIs forsubframe nu. The special case of identical information in alltransmission-related parameters can also be solved by one of thepresented embodiments.

If the behavior of the UE is undefined, the UE is free to do, forinstance, any of the following:

-   -   a) Transmit PUSCH in subframe nu according to the DCI received        in subframe n1    -   b) Transmit PUSCH in subframe nu according to the DCI received        in subframe n2    -   c) Not transmit any PUSCH in subframe nu if the two received        DCIs are inconsistent

Due to this uncertainty, an eNB scheduler may advantageously avoidtransmitting conflicting grants. Consequently, the scenario ofconflicting granted resources would mainly occur due to a falsedetection of a DCI at any point of time. However, there may be reasonswhy the eNB might intentionally send a new DCI in subframe n2:

-   -   The channel conditions have changed and the eNB would like to        override an earlier DCI.    -   The earlier DCI was granting multiple subframes and the eNB        would like to update e.g. the LBT or starting/ending symbol to        changing conditions, or optimize the transmission parameters        such as RV or MCS for a single subframe within the plurality of        granted subframes.    -   The eNB would like to extend or shorten the number of granted        subframes e.g. in a two-stage grant case after the first stage        grant has been transmitted.

In addition, there could even be some uncertainty whether especially amulti-subframe grant should be processed by the UE in subframes afterthe conflict takes place, i.e. in subframes nu+1 and later.

Two stage grant is a procedure in which a first-stage grant for a UEprovides high level information (e.g. RB allocation, MCS etc.) and asecond-stage grant by a common control information can schedule(trigger) PUSCH transmissions following MSF or SSE for certain ULsubframes. In particular, the first-stage grant is received in a firstDCI for a specific UE. The second-stage grant is received with a secondDCI possibly addressed commonly to a plurality of UEs. Both DCIs mayspecify respective scheduling delays, which are summed after receptionof the second-stage DCI in order to determine the subframe fortransmitting data.

The two-stage grant procedure is further described in Section 8.0 of the3GPP TS 36.213, v14.0.0 from September 2016, available at www.3gpp.org.

It is noted that the first-stage grant and the second-stage grant do notcorrespond to the first and second grant mentioned above. Among thefirst-stage grant and the second-stage grant, it will advantageously bethe second-stage grant (in the role of the first and/or the second grantmentioned above) which may cause conflict with possible other grantsbecause it is the second-stage grant which actually triggers thetransmission and thus determines the precise subframe location for thedata transmission.

When a conflict occurs, according to one example, both conflictingmessages are discarded in order to avoid misinterpretations andinappropriate behavior of the receiving node especially in case oferroneous control information reception. Thus, one of possible solutionfor the conflict of grants for the same subframe is to discard bothgrants. The effect is that in the subframe nu for which two grants werereceived no transmission takes place. However, such solution mayintroduce some further delays in the data transmission which is notcompliant with the aims to provide a reduced shared channel transmissiondelay. Moreover, the missed transmission opportunity also results inwasting or losing resources especially in a shared radio medium such asan unlicensed carrier. For example, if the node does not transmitanything during a subframe that is scheduled by two grants, the effectis that the channel is vacated (i.e. unused) by the node according tothis solution, which may lead other contenders of the channel to detectthe channel as not busy and thereby bears the risk of other nodesoccupying the channel.

Accordingly, the present disclosure defines UE behavior and inparticular which of two grants is to be followed in the conflictingsubframe and/or later subframes.

It is noted that according to the present disclosure, both grantsscheduling conflicting transmissions on the same subframe may bediscarded for that subframe. However, if one of the grants is amulti-subframe grant, the subframes following the discarded subframe maybe used for the scheduled multi-subframe transmission. This will beexplained below in greater detail.

Moreover, even if the description concentrates on two grants receivedand resulting in transmission conflict in the same subframe, the presentdisclosure is not limited thereto. There may be more than two grants forthe same subframe. Then, similar rules are applicable for selectingwhich grant to follow as in the case of two grants.

According to an embodiment, there is a conflict caused by two grants oneof which is a single subframe grant and the other one of which is amulti-subframe grant. If the data transmitting node receives such twogrants, it obeys the single subframe grant. This approach has anadvantage that the scheduling node is able to override specific singlesubframes compared to the multi-subframe grant. This may be particularlyrelevant for triggering for instance aperiodic channel state indicationreporting or sounding reference signals.

In the 3GPP standardization, it has been recently agreed for themulti-subframe scheduling that a DCI (0B or 4B) shall be able to triggerSounding Reference Signals (SRS) and/or Channel State Information (CSI).However, there are fixed rules according to which in one of the multiplesubframes the SRS and/or CSI is triggered, which means that theflexibility of triggering the SRS and/or the CSI is limited incomparison with the SSF grants. If it is desired to trigger SRS/CSI in aparticular subframe which is not addressable by the MSF DCI, thenoverriding the MSF by the SSF can allow that.

In particular, the agreements for the MSF DCIS are briefly summarized inthe following. For MSF DCI format 4B, the current 2-bit SRS triggeringfield is utilized. An SRS subframe indication is included indicating theapplicable SRS parameter set configuration (which is provided via RRC).For MSF DCI format 0B, existing SRS triggering bit and 1 additional bitare used for SRS triggering and subframe indication. The four states aredefined as no triggering, triggering in the first, in the second or inthe last subframe. Thus, it is not possible to trigger SRS in two ormore of the multiple subframes or the subframes between the second andthe last subframes.

The CSI request in DCI format 0B/4B applies to 2nd scheduled subframe ifNmax=2, and otherwise to the penultimate scheduled subframe. Here, Nmaxis the configurable maximum number of subframes that can be scheduled byDCI format 0B/4B. Thus, there is no further flexibility for CSItriggering envisaged currently.

However, it is noted that a conflict may also occur as a result oftransmission error, i.e. if a DCI is wrongly detected by a UE due to anundetected error.

In this embodiment, according to a first alternative, the datatransmitting node obeys the single subframe grant in subframe nu forwhich this grant has been received. Moreover, it obeys the multiplesubframe grant for the subframes following the subframe nu. Thisapproach is illustrated in FIG. 5.

FIG. 5 shows on the time axis 510 subframes numbered n1 to n2 and nu−2to nu+2. In the subframe n1 a multi-subframe DCI is transmitted whichgrants to the UE resources in four subframes nu−1 to nu+2. Moreover, insubframe n2 a single subframe DCI is transmitted which grants to thesame UE resources in subframe nu. Accordingly, there are two grantsreceived by the UE for the subframe nu. The UE behavior in this scenariocan be seen for the four granted subframes 520 as follows: in subframenu−1 the UE will transmit data according to the MSF. In subframe nu inwhich there is a conflict between the MSF grant and a SSF grant, the SSFgrant will be followed. In the subframes nu+1 and nu+2 after theconflicting subframe nu, the MSF grant is followed. It is noted that theterm “following” or “obeying” a grant in this context indicate that thetransmission parameters indicated in the grant are adopted fortransmission of the data. The transmission parameters, as alreadydiscussed in the background section, may be one or more of resourceblock assignment, modulation and coding scheme, carrier indicator, HARQinformation, power control commands, reference signal information CSI orSRS trigger, hopping information, multi-cluster information or the like.

The bottom line of FIG. 5 shows a scenario in which in subframe n1 asingle subframe DCI is received at the UE and in subframe n2 another,multi-subframe DCI, is received by the same UE. The single subframe DCIincludes the resource allocation in subframe nu. The multi-subframe DCIincludes the resource allocation for four subframes nu−1 to nu+2,including subframe nu. The behavior of the UE is illustrated for thefour subframes 530 as follows: in subframe nu−1 the UE will transmitdata according to the MSF. In subframe nu the UE will transmit dataaccording to the SSF. In the remaining subframes nu+1 and nu+2 the UEwill transmit data according to the MSF again.

This approach provides the advantage of keeping the overhead low in casethe scheduling node (eNodeB) wants to override only a single subframewithin a multi-subframe grant since the rest of MSF is followed.

On the other hand, there may be scenarios in which it is beneficial tofollow only the SSF grant and not to resume the MSF grant transmissionin the later subframes. Such example is shown in FIG. 6. In particular,FIG. 6 shows time axis 610 with subframe index of the subframes n1 to n2and nu−2 to nu+2. In subframe n1, an MSF DCI is received by the UE withresource allocation for subframes nu−1 to nu+2. Moreover, in subframen2, an SSF DCI is received by the same UE for subframe nu alreadyincluded in the MSF DCI allocation. The UE behavior for the foursubframes 620 is as follows. The UE transmits data in subframe nu−1according to the MSF and in subframe nu according to the SSF. Aftertransmitting the data in the subframe nu, the UE will not resume thetransmission in the remaining two subframes nu+1 and nu+2. Accordinglyin these two subframes, the UE will not transmit at all. This approachprovides the advantage of avoiding excessive uplink transmissions incase that one of the two detected grants is a false alarm which meansthat there was in fact no grant transmitted for that UE.

The last row of FIG. 6 shows a similar scenario in which an SSF DCI isreceived in subframe n1 and an MSF DCI is received in subframe n2. TheSSF DCI provides resource reservation for subframe nu (for instance byusing the scheduling delay field of the DCI) whereas the MSF DCIprovides resource reservation for four subframes nu−1 to nu+2. The UEbehavior in this case for the four subframes 630 is the same as above:the UE shall transmit data according to the MSF grant in subframe nu−1and according to the SSF grant in subframe nu. In the remainingsubframes nu+1 and nu+2 of the MSF grant, no transmission takes place.

According to another embodiment, upon receiving two grants for the samesubframe, the UE follows the grant that has been received later in time.This approach provides an advantage that that the scheduling node canoverride any later DCI to adapt to a new situation. This is particularlybeneficial if an additional start or end gap is necessary forlisten-before-talk procedures or if the channel should be kept longer orreleased earlier than planned and indicated before. It enables thescheduling node to change its early decisions and thus provide moreflexibility.

This approach is illustrated in FIG. 7. In this example, the UEtransmits data in subframe nu according to the grant received later intime and follows the MSF grant in subframes following subframe nu, ifapplicable (i.e. if there are subframes allocated by the MSF grantfollowing subframe nu). In particular, FIG. 7 shows a time axis 710 withsubframes having index n1 to n2 and nu−2 to nu+2. In subframe n1, the UEreceives an MSF DCI with resources allocated in four subframes nu−1 tonu+2. Moreover, in subframe n2 following in time subframe n1, the UEreceives an SSF DCI with resources allocated in one subframe nu. The UEwill transmit data in the four subframes 720 in the allocated resourcesas follows: in subframe nu−1 the data are transmitted according to theMSF grant. In subframe nu, the data are transmitted according to the SSFgrant since it was received more recently than the MSF grant. The datatransmission in subframes nu+1 and nu+2 takes place according to the MSFgrant.

The bottom line of FIG. 7 shows another scenario, in which the SSF DCIis received in subframe n1 which is located in time before subframe n2in which the MSF DCI is received. Both the SSF and the MSF grantsoverlap since they both allocate resources in the same subframe nu. Inthis scenario, since the MSF grant is the more recent of the two grants,the entire data transmission in the four subframes nu−1 to nu+2 denotedwith reference numeral 730 is performed according to the MSF grant. Theapproach shown in FIG. 7, according to which the most recent grant isselected, provides the advantage that the most recent grant is followedso that adaption on the recent state of the channel and system ispossible and the resources are well utilized since the MSF grant isfollowed as far as possible.

It is noted that—as is shown in FIG. 7 (as well as FIGS. 5 and 6),subframes n1 and n2 are not necessarily adjacent. Subframes n1 and n2may be adjacent or there may be any number of subframes in between (anynumber within the reasonable scheduling delay in which resources for thesame subframe may be scheduled, which is basically a system parameter).

Another alternative embodiment is shown in FIG. 8. FIG. 8 illustrates anapproach according to which the UE obeys the later grant in subframe nuand does not resume transmission according to the other grant(overlapping with the later grant) in subframes following subframe nu(if any). In particular, FIG. 8 shows the time axis 810 with subframeshaving indexes from n1 to n2 and nu−2 to nu+2. According to a firstoption, an MSF DCI with grant for subframes nu−1 to nu+2 is received insubframe n1. Moreover, an SSF DCI carrying grant for subframe nu isreceived in subframe n2. The UE behavior in the four subframes 820allocated by the MSF grant is as follows: Data are transmitted accordingto the earlier MSF grant in subframe nu−1. In subframe nu, the laterreceived SSF grant is preferred and the data transmission is performedaccordingly. After selecting the SSF grant for subframe nu, thetransmission in the remaining subframes nu+1 and nu+2 reserved by theMSF grant is not performed.

The bottom line of FIG. 8 shows another scenario, in which the SSF DCIis received before receiving the MSF DCI for transmission of data in thesame subframe nu. The behavior of the UE in the four subframes 830 isthat the UE transmits data in all four subframes nu−1 to nu+2 for whichthe MSF grant was received according to the MSF grant, i.e. using thetransmission parameters set by the MSF DCI. In this embodiment, in whichthe most recent grant is to be followed, resources are only unused inthe first option, when the SSF is the more recent grant. This approachmay be beneficial in cases the MSF was a false alarm corrected by theSSF.

In the present disclosure, in terminology of 3GPP systems, the SSF DCImay be DCI format 0A or 4A, or a DCI format 0B or 4B that reservestransmission resources in just a single subframe, whereas the MSF DCImay be DCI format 0B or 4B that reserves transmission resources in morethan one subframe. According to an alternative terminology of 3GPPsystems, the SSF DCI may be DCI format 0A or 4A, whereas the MSF DCI maybe DCI format 0B or 4B.

It is noted that the present disclosure is not limited to the abovedescribed embodiments. In general, the present disclosure provides anapproach which avoids discarding all grants which are received forresources in the same subframe. This is achieved by defining a rulewhich is then applied at the data transmitting side after detecting theconflict.

For instance, it may be advantageous, if two inconsistent DCIs arereceived with resource allocation for the same subframe nu, not totransmit anything in the subframe nu. Here, the inconsistent DCIS meantwo DCIS which differ at least with one transmission parameter, i.e. inthe context of LTE indicate different PUSCH parameters. This approach isparticularly well applicable if conflicts due to false alarm should beavoided as much as possible.

In other words, a data transmitting device may be provided fortransmitting data to a data receiving node over a wireless channel in acommunication system, the data transmitting device comprising: grantreceiving circuitry for receiving a first resource grant for a datatransmission in a subframe and a second resource grant for a datatransmission of data in said subframe, the first and the second resourcegrant differing in at least one transmission parameter. The datatransmitting device further comprises transmission control circuitry forjudging whether or not at least two resource grants were received forthe same subframe and for controlling a transmitter (also part of thedata transmitting device) not to transmit data in that subframe.

However, it is noted that in case one of the grants is an MSF grant, thetransmission may still take place in the subframes reserved by the MSFand following the conflicting subframe nu. In other words, thetransmission control circuitry controls the transmitter to performtransmission in those subframes reserved by the first and/or by thesecond grant, for which there is no conflict of DCIs, i.e. for whichonly one transmission parameter set was received.

This is illustrated in FIG. 9. FIG. 9 shows subframes n1 to n2 and nu−2to nu+2 in a time domain 910. In subframe n1, a multi-subframe grant isreceived for subframes nu−1 to nu+2. In subframe n2, an SSF grant isreceived for subframe nu. In this example, the UE receives the twogrants and performs or does not perform transmission in the foursubframes 920 as follows: the transmission in subframe nu−2 is performedaccording to the transmission parameters specified in the MSF grant(received in subframe n1). In subframe nu, no transmission is performedsince for this subframe, two different DCIs have been received. However,in the subframes nu+1 and nu+2, the transmission as configured by theMSF DCI is resumed, irrespectively of whether the MSF or the SSF grantarrived later (see transmission in the four subframes 930 in the lastrow of FIG. 9). In general, the transmission takes place in anysubframes for which no inconsistent DCIs have been received, i.e. insubframes for which there is no DCI conflict. Especially in case thetransmissions are scheduled for a shared radio medium such as anunlicensed carrier, it may be beneficial to undergo an additional LBTprocedure before the transmission in subframe nu+1 is resumed. If thereis no transmission occurring in subframe nu, it implies that othercontenders for the radio medium may sense the medium as vacant (i.e. notbusy) and therefore initiate their own transmissions on the medium.Therefore an LBT procedure before resuming transmissions in subframenu+1 can avoid potential interference.

In other words, according to an embodiment, the data transmitting deviceincludes a medium sensing unit (circuitry) for sensing whether or not atransmission is taking place in certain resources. Moreover, thetransmission control circuitry is configured to instruct the mediumsensing unit to perform the sensing when resuming transmission of dataaccording to multiple subframe grant for the subframes followingsubframe nu, i.e. for the frames following the conflicted subframe. Asdescribed above, in subframe nu no transmission takes place, i.e. noneof the conflicting grants is followed.

Alternatively, it may be advantageous not to resume transmissionaccording to the MSF since there is a risk that other transmitter sensedin the subframe nu and detected that no transmission occurred and thusis transmitting in subframe nu+1 and/or following subframes. In absenceof an additional LBT, this scenario may then lead to collisions betweenthe UE and the other device(s). The other devices may be any devicesfrom the unlicensed band, such as WiFi or the like. Thus, especially inabsence of an additional LBT, the UE may advantageously not transmitdata in the subframes following the conflicting subframe.

FIG. 10 illustrates the case in which the transmission is not resumed.In particular, in subframe n1 out of subframes in the time domain 1010,an MSF grant is received for four frames nu−1 to nu+2. However, out ofthe four subframes 1020, the transmission takes only place in subframenu−1, i.e. before subframe nu. In subframe nu, in which the conflict ofDCI occurs as well as in the following subframes, no transmission takesplace. As can be seen in the bottom line of FIG. 10, the sametransmission pattern 1030 is adopted in the case in which the SSF grantis received before the MSF grant. Especially in case the transmissionsare scheduled for a shared radio medium such as an unlicensed carrier,it may be beneficial to generally not resume transmissions in subframenu+1 as mentioned above. If there is no transmission occurring insubframe nu, it implies that other contenders for the radio medium maysense the medium as vacant (i.e. not busy) and therefore initiate theirown transmissions on the medium. Therefore not resuming transmissions insubframe nu+1 can avoid potential interference. This is particularlyapplicable if the data transmitting circuitry is not quickly capable ofswitching from transmitting e.g. in subframe nu−1 to receiving insubframe nu for the purpose of sensing the channel according to an LBTprocedure and switching back to transmitting in subframe nu+1. It isfurther beneficial if it is unclear for the data transmitting devicewhat kind of LBT parameters are applicable, i.e. if it is not aware ifthe channel is still being kept reserved e.g. by the central node (suchthat other contenders cannot grab the channel) or not, or in case theduration during which the LBT procedure would need to sense the channelas clear is unclear. In other words, it may be difficult to perform LBTfor subframe nu+1 and then still transmit in that subframe. If the UEcannot perform the LBT efficiently, a behavior based on discarding theconflicting grants for all granted subframes may be advantageous.

It is also possible to define the UE behavior based on UE capabilities.

According to an embodiment, if there is a conflict between an SSF and anMSF, the SSF grant is always ignored. In other words, irrespectively ofthe time of reception of the two grants, the SSF grant is not selected.Rather, the MSF grant is selected and the data are transmitted inaccordance with the transmission parameters defined therein in thespecified multiple subframes. This embodiment is beneficial for theimplementation of the coding chain in the UE implementation. As an MSFis capable of assigning multiple subframes, it implies that thetransmission of multiple transport blocks are granted, where the datasegmentation can be facilitated in a uniform way. Since the dataarriving from upper communication layers arrives in a pipeline fashion,it is beneficial if it is possible to process the data in a uniform way(as facilitated by an MSF DCI) compared to the case that the UE needs toprovide for the possibility that a different data packet size isinterspersed by an SSF DCI, which may easily cause data fragmentation inthe pipeline and/or higher layer reordering procedures to establish anin-sequence delivery of data to upper communication layers at thereceiver.

According to a further embodiment, the UE obeys the grant that has beenreceived earlier in time. Such approach provides an advantage from a UEimplementation perspective because the PUSCH transmission will obey thefirst grant in all cases. Thus, it is not necessary to implement anoverriding or stopping mechanism for the case that a later DCI addressesthe same subframe. Similar to the embodiment of always ignoring the SSFgrant, there are resulting simplification benefits in the upper layerprocedures such as data segmentation, data fragmentation, andreordering.

According to another embodiment, the UE obeys the grant which is morereliable as seen by the UE. In other words, there is predefined rule forevaluating reliability and irrespectively of the type of the grant andthe time of receiving the grant, among the received grants the one mostreliable is selected.

The reliability may be measured or evaluated in various different ways.The present disclosure is not limited to one of them. For instance, thegrant protected with CRC having more bits is selected. Here it isassumed that the longer CRC provides more reliability in detecting anerror in the received DCI. For example, a CRC with 16 bits has an higherundetectable error ratio compared to a CRC with 24 bits by a factor of256. Accordingly, the DCI with more bits dedicated to CRC is selectedfor data transmission as it is assumed that probability of false alarmwith larger CRC is smaller. Here, the term “false alarm” refers to acase in which a DCI is detected at the UE, where there was no granttransmitted to that UE. A consequence of following such erroneouslyreceived grant is a data transmission by the UE in resources which werenot reserved for it. Such resources may have been reserved for anotherUE and parallel transmission by two different UEs in the same resourcesmay likely result to reception of corrupted data at the base station. Inaddition, such a false alarm leads to wasted power that is transmittedby the UE since the eNB is not aware of the corresponding transmission.

It is noted that currently in LTE, there is no variable CRC length forDCI available. However, in NR or in other systems to which thisdisclosure also applies, the CRC may advantageously be configurableand/or may have different length for different types of DCI.

Another possibility to evaluate (measure) the reliability is based onthe number of predefined-value bits or the length of the padding.Accordingly, a DCI with more reserved bits, and/or with more bits thathave a pre-defined value, and/or with more bits spent for padding may beselected for data transmission. This criterion is particularly relevant,if the UE uses the padding bits and/or the predefined-value bits forchecking the correctness of the reception.

For instance, according to an exemplary UE implementation, the UEreceives a DCI and, within the DCI one or more padding bits. The paddingbits are set to a known predefined value at the transmitter (basestation). The UE then validates, whether or not the received paddingbits have the expected predefined values. If the padding bits do nothave the expected predefined values, it may be concluded that atransmission error occurred and the DCI is treated as incorrect orinconsistent. Accordingly, the padding bits provide some redundancywhich can be also used to determine the reliability of the received DCI.

Furthermore, some DCI fields may have a fixed predefined value dependingon the format of the DCI. Moreover, there may be only certaincombinations of parameter values possible within the DCI. Any suchpredefined values or combination rules may be used at the receiver (UE)to check the validity of the DCI and thus also serve as a kind ofreliability check. For instance, Section 9.2 of 3GPP TS 36.213, v13.3.0from September 2016 describes a validation of PDCCH, EPDCCH and MPDCCHfor semi-persistent scheduling. In particular, a UE validates asemi-persistent scheduling PDCCH (i.e. DCI received in the PDCCH) onlyif certain conditions are met such as successful CRC check and certaintransmission parameters set to respective predefined values.

Still further criteria for evaluating the reliability is the estimatedSINR. A grant received with higher estimated SINR is selected for thenext data transmission.

Another option is to measure reliability by evaluating coding rate(ratio between the information bits and the total number of bitsincluding also redundancy added by the forward error detection and/orcorrection code). In LTE, the control information is rate matchedthrough puncturing and repetition to the number of bits that can becarried by a physical downlink control channel, considering the numberof resources and/or modulation scheme being used for transmission ofsaid channel.

It is noted that further options are possible such as number of resourceelements used for transmission. It is assumed that the more the resourceelements, the more reliable is the transmission. Accordingly, the grantwith the highest number of resource elements for its conveying isselected.

The above criteria may be used alternatively or in any combination. Forinstance a weighted average (linear combination) of two or more of theabove criteria is possible. However, the present disclosure is notlimited thereto and any measure reflecting the reliability may beemployed. For this measure one or more of the above parameters may beincluded and contribute linearly or non-linearly to the measure value.

The present disclosure is not limited to handling conflicts of two(different) grants. There may be three or more grants for the samesubframe, i.e. carrying allocation for the same UE in the same subframe,with possibly different content (transmission parameters). As mentionedabove, for different scenarios, different handling of the conflicts maybe beneficial. One possible scenario is that a DCI is detected at a UEwhile there was no DCI sent to that UE. This is called in this text“false alarm”. It is beneficial to reduce false alarms, as they wasteresources and increase interference. Another possible scenario isintentional provision of two different grants for the same subframe bythe base station. As explained above, this may be the case if a basestation wishes to adapt the transmission parameters to the recentsituation such as channel quality and load. Since for resolving theintentional and unintentional conflicts at the UE different respectiveapproaches may be suitable, it is advantageous to enable configurationof the desired UE behavior. In particular, according to an embodiment,the base station or another network element is capable of configuringthe UE to adopt or not to adopt at least one of the above describedapproaches upon conflict of two or more grants, such as:

-   -   Not transmitting data in a subframe for which a plurality of        different grants were received.    -   Not transmitting data in any subframe specified in a plurality        of different grants which specify at least one common subframe.    -   Not transmitting data in the subframe for which a plurality of        different grants were received, but transmitting data in the        remaining subframes specified by the plurality of grants.    -   Transmit data in a subframe according to the most recently        received grant among a plurality of grants received for said        subframe.    -   Transmit data in a subframe according to the first received        grant among a plurality of grants received for said subframe.    -   Transmit data in a subframe according to the most reliable grant        among a plurality of grants received for said subframe.    -   Between MSF and SSF grants prefer SSF grant(s).    -   Between MSF and SSF grants prefer MSF grant.

The criteria for selecting which of multiple received grants to follow,a combination of the above criteria may be used and signaled as aconfiguration for the UE behavior. For example, if there are more thantwo grants, two of them SSF and one MSF, the SSF grants may be generallyselected and between the SSF the most recent one may be selected. Othercombinations are also possible.

According to an exemplary UE behavior, if the UE detects conflictingPUSCH assignments for the same subframe nu, the UE shall transmit PUSCHaccording to the following sequence of priorities:

-   -   1) If the conflict results from a single-subframe grant and a        multi-subframe grant, the UE follows the single-subframe grant.    -   2) If the conflict is not resolved by step 1), the UE follows        the more recently received grant. In case of triggered        scheduling, the UE considers the reception of the second stage        as the receiving time of the grant.    -   3) Behavior for the remaining (without conflicting DCI)        subframes of an MSF grant may be specified, e.g. that the        transmission of data shall be performed in these subframes.

This may correspond to one of the configurable behaviors. Another onemay be not to transmit data in the conflicting subframe(s).

The configuration may be performed, for instance by means of semi-staticsignaling such as RRC in LTE. However, the present disclosure is notlimited thereto and in general, any kind of signaling may be applicable.

However, the present disclosure is not limited thereto and, in general,one of the above defined UE behaviors may be predefined in a standard.Definition in standard provides the advantage that both the base stationand the UE know how the UE will behave, which reduces themisunderstandings and overhead (in terms of time, power and otherresources). Alternatively, the UE may adopt one of the above approachesas an implementation specific approach. The node be then has to detectupon receiving data, which grant was followed. This may be performed,for instance by blind detection (i.e. trying the decoding of thetransmitted data according to each of the conflicting grants and decidebased on the results, which decoding was more reliable). However, suchapproach is less robust.

The above description provides examples which are described with thehelp of 3GPP terminology. However, as is clear to those skilled in theart, the present disclosure is not limited thereto. For instance, theterm “subframe” may generally mean any predefined duration in the timedomain which is allocable to a user device. Moreover, the term “grant”means any indication of resources in which data is to be received ortransmitted. This may include specification of the time and/or frequencyresource (or any other such as space and/or code) for the transmission,but also further transmission parameters such as MCS or the like whichdefine how the data are to be transmitted.

Moreover, it is noted that the above examples show four subframesallocated by a single multiple subframe DCI. However, the presentdisclosure is not limited thereto. The MSF grant is configurable and mayinclude resource allocation for less (e.g., 2 or 3) or more (more than4) subframes. The same approached described above are applicableirrespectively of the particular number of subframes per MSF grant.

In summary, the present disclosure provides handling for the case ofdifferent DCI addressing the same UL subframe, and proposes toprioritise DCIs according to their reception time or whether single ormultiple subframes are assigned or according to other criteria such asreliability of the received grant, or a combination of these criteria.

FIG. 11 shows a data transmitting device 1210 for transmitting data to adata receiving node 1260 over a wireless channel in a communicationsystem 1200. The communication system may be a system such as LTEoperating in licensed or unlicensed band and may at least comprise auser equipment and a base station. It is noted that a user equipment mayalso implement base station functionality with respect to other userequipment. The data transmitting device may be the UE and the datareceiving device may be the base station in uplink and vice versa indownlink. The base station operates as a scheduling node, providingresource grants for the UE.

The data transmitting device 1210 comprises a grant receiving unit(circuitry) 1220 for receiving a first resource grant 1272 a for a datatransmission in a subframe and a second resource grant 1272 b for a datatransmission of data in said subframe.

It is noted that the first and the second grant are typicallytransmitted in different subframes. Based on the reception time(subframe), the data transmitting device 1210 is capable of determiningthe location of the resources in a particular subframe. Either there isa predefined offset between the grant reception and the datatransmission, or the offset is signaled in the grant, or a combinationof both. The resources may be further specified within the grant interms of frequency and/or coding and modulation to be applied andfurther transmission parameters. In case of LTE, the grant may becarried in form of a DCI, the downlink control information.

The data transmitting device 1210 further comprises a transmissioncontrol unit (circuitry) 1230 for selecting according to which of thefirst resource grant and the second resource grant data are to betransmitted in the subframe; and a transmission unit (transmitter) 1240for transmitting the data 1242 in the subframe according to the selectedfirst grant or second grant.

The data receiving device 1260 for transmitting data to a datatransmitting device 1210 over the wireless channel in a communicationsystem 1200. The data receiving device 1260 comprises a granttransmitting unit (circuitry) 1270 for transmitting a first resourcegrant 1272 a for a data transmission in a subframe and a second resourcegrant 1272 b for a data transmission of data in said subframe to thedata transmitting device 1260.

The data receiving device 1260 further comprises a reception controlunit (circuitry) 1280 for determining according to which of the firstresource grant and the second resource grant data are to be received inthe subframe; and a reception unit (receiver) 1290 for receiving thedata in the subframe according to the determined first grant or secondgrant.

The data transmitting device 1210 and/or the receiving device 1260 mayfurther include the transmitter and receiver. The transmitter mayinclude the antenna(s), amplifier(s), modulator, and coder, i.e.functional units and devices which enable the transmission/reception ofthe data and the grants respectively in accordance with the wirelessinterface specification. The transmitter may be part of the transmissionunit (transmitter) 1240.

Similarly, the data transmitting device 1210 and/or the data receivingdevice 1260 may further include receiver with the antenna(s),amplifier(s), demodulator, decoder and other functional units anddevices which enable transmission/reception of the data and grantsaccording to the wireless interface specification.

FIG. 12 shows on the left hand side a method for transmitting data froma data transmitting node to a data receiving node over a wirelesschannel in a communication system. The method comprises receiving 1310,1320 a first resource grant for a data transmission in a subframe and asecond resource grant for a data transmission of data in said subframe.Moreover, the method comprises selecting 1330 according to which of thefirst resource grant and the second resource grant data are to betransmitted in the subframe; and transmitting 1340 the data in thesubframe according to the selected first grant or second grant.

Correspondingly, a method for receiving data from a data transmittingdevice over a wireless channel in a communication system is shown on theright hand side of FIG. 12 and transmitting 1360, 1370 a first resourcegrant for a data transmission in a subframe and a second resource grantfor a data transmission of data in said subframe to the datatransmitting device; determining according to which of the firstresource grant and the second resource grant data are to be received inthe subframe; and receiving 1380 the data in the subframe according tothe determined first grant or second grant.

The determining step may be performed either based on the knowledge ofthe UE behavior or based on “trial-and-error” multiple hypothesestesting by trying to decode the data with transmission parameters of theconflicting grants and checking the result.

For example, the transmission parameters indicated by the first grantand second grant differ in at least one parameter.

According to an embodiment, the first resource grant is a multiplesubframe grant indicating allocation of resources for a plurality ofsubframes of the communication system; and the second resource grant isa single subframe grant indicating allocation of resources for a singlesubframe of the communication system.

According to another embodiment, the single subframe grant is selected.For instance, the first resource grant is selected when the firstresource grant was received after receiving the second resource grant,and the second resource grant is selected when the second resource grantwas received after receiving the first resource grant.

Advantageously, when the first resource grant or the second resourcegrant, which was not selected for data transmission in said subframe, isa multiple subframe grant indicating allocation of resources for aplurality of subframes of the communication system, data are transmittedin the allocated plurality of subframes according to the multiplesubframe grant except for said subframe.

Alternatively, when the first resource grant or the second resourcegrant, which was not selected for data transmission in said subframe, isa multiple subframe grant indicating allocation of resources for aplurality of subframes of the communication system, data are nottransmitted according to the multiple subframe grant in the allocatedplurality of subframes following said subframe,

According to an embodiment, the multiple subframe grant is selected.

According to an embodiment, the first resource grant is selected whenthe first resource grant was received before receiving the secondresource grant, and the second resource grant is selected when thesecond resource grant was received before receiving the first resourcegrant.

According to a further embodiment, a measure of reliability is obtainedfor the first resource grant and the second resource grant, and amongthe first and the second resource grant the one for which thereliability measure indicated higher reliability is selected.

The reliability measure is advantageously determined according to one ormore of the following parameters:

-   -   Cyclic Redundancy Check, CRC, length for the control information        carrying the grant,    -   Number of bits with predefined values in the control information        carrying the grant,    -   Number of padding bits in the control information carrying the        grant,    -   Estimated value of the Signal to Interference and Noise Ratio,        SINR,    -   Coding rate for the control information carrying the grant, and    -   Number of resource element used to carry the control information        carrying the grant.

For instance, at least one of the first resource grant and the secondresource grant is received within a dedicated control informationsignaling from the data receiving node, the dedicated controlinformation specifying one or more of the modulation and coding scheme,a single subframe or multiple subframes in which resources areallocated, a scheduling delay indicating the location of the allocatesone or more subframes.

In accordance with another embodiment, a (non-transitory) computerreadable medium is provided with a program stored therein, which whenrunning on a computer, executes the steps of the above described method.

Hardware and Software Implementation of the Present Disclosure

Other exemplary embodiments relate to the implementation of the abovedescribed various embodiments using hardware, software, or software incooperation with hardware. In this connection a user terminal (mobileterminal) and an eNodeB (base station) are provided. The user terminaland base station is adapted to perform the methods described herein,including corresponding entities to participate appropriately in themethods, such as receiver, transmitter, processors.

It is further recognized that the various embodiments may be implementedor performed using computing devices (processors). A computing device orprocessor may for example be general purpose processors, digital signalprocessors (DSP), application specific integrated circuits (ASIC), fieldprogrammable gate arrays (FPGA) or other programmable logic devices,etc. The various embodiments may also be performed or embodied by acombination of these devices. In particular, each functional block usedin the description of each embodiment described above can be realized byan LSI as an integrated circuit. They may be individually formed aschips, or one chip may be formed so as to include a part or all of thefunctional blocks. They may include a data input and output coupledthereto. The LSI here may be referred to as an IC, a system LSI, a superLSI, or an ultra LSI depending on a difference in the degree ofintegration. However, the technique of implementing an integratedcircuit is not limited to the LSI and may be realized by using adedicated circuit or a general-purpose processor. In addition, a FPGA(Field Programmable Gate Array) that can be programmed after themanufacture of the LSI or a reconfigurable processor in which theconnections and the settings of circuits cells disposed inside the LSIcan be reconfigured may be used.

Further, the various embodiments may also be implemented by means ofsoftware modules, which are executed by a processor or directly inhardware. Also a combination of software modules and a hardwareimplementation may be possible. The software modules may be stored onany kind of computer readable storage media, for example RAM, EPROM,EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc. It shouldbe further noted that the individual features of the differentembodiments may individually or in arbitrary combination be subjectmatter to another embodiment.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present disclosure asshown in the specific embodiments. The present embodiments are,therefore, to be considered in all respects to be illustrative and notrestrictive.

In summary, the present disclosure relates to a data transmittingdevice, data receiving device and the corresponding data transmittingmethod and data receiving method for transmitting/receiving data over awireless channel in a communication system. In particular, a firstresource grant is received for a data transmission in a subframe and asecond resource grant for a data transmission of data in said subframe.Then, it is determined, according to which of the first resource grantand the second resource grant data are to be transmitted in thesubframe; and the data is transmitted in the subframe according to theselected first grant or second grant.

What is claimed is:
 1. A data transmitting device for transmitting datato a data receiving node over a wireless channel in a communicationsystem, the data transmitting device comprising: grant receivingcircuitry for receiving a first resource grant for a data transmissionin a subframe and a second resource grant for a data transmission ofdata in said subframe; transmission control circuitry for selectingaccording to which of the first resource grant and the second resourcegrant data are to be transmitted in the subframe; and a transmitter fortransmitting the data in the subframe according to the selected firstgrant or second grant.
 2. The data transmitting device according toclaim 1, wherein the transmission parameters indicated by the firstgrant and second grant differ in at least one parameter.
 3. The datatransmitting device according to claim 1, wherein the first resourcegrant is a multiple subframe grant indicating allocation of resourcesfor a plurality of subframes of the communication system, and the secondresource grant is a single subframe grant indicating allocation ofresources for a single subframe of the communication system.
 4. The datatransmitting device according to claim 3, wherein the transmissioncontrol circuitry selects the single subframe grant.
 5. The datatransmitting device according to claim 2, wherein the transmissioncontrol circuitry: selects the first resource grant when the firstresource grant was received after receiving the second resource grant,and selects the second resource grant when the second resource grant wasreceived after receiving the first resource grant.
 6. The datatransmitting device according to claim 1, wherein when the firstresource grant or the second resource grant, which was not selected fordata transmission in said subframe, is a multiple subframe grantindicating allocation of resources for a plurality of subframes of thecommunication system, the transmitter transmits data in the allocatedplurality of subframes according to the multiple subframe grant exceptfor said subframe.
 7. The data transmitting device according to claim 1,wherein when the first resource grant or the second resource grant,which was not selected for data transmission in said subframe, is amultiple subframe grant indicating allocation of resources for aplurality of subframes of the communication system, the transmitter doesnot transmit data according to the multiple subframe grant in theallocated plurality of subframes following said subframe.
 8. The datatransmitting device according to claim 3, wherein the transmissioncontrol circuitry selects the multiple subframe grant.
 9. The datatransmitting device according to claim 2, wherein the transmissioncontrol circuitry: selects the first resource grant when the firstresource grant was received before receiving the second resource grant,and selects the second resource grant when the second resource grant wasreceived before receiving the first resource grant.
 10. The datatransmitting device according to claim 2, wherein the transmissioncontrol circuitry: obtains a measure of reliability for the firstresource grant and the second resource grant, and selects among thefirst and the second resource grant the one for which the reliabilitymeasure indicated higher reliability.
 11. The data transmitting deviceaccording to claim 10, wherein the reliability measure is determinedaccording to one or more of the following parameters: Cyclic RedundancyCheck, CRC, length for the control information carrying the grant,Number of bits with predefined values in the control informationcarrying the grant, Number of padding bits in the control informationcarrying the grant, Estimated value of the Signal to Interference andNoise Ratio, SINR, Coding rate for the control information carrying thegrant, and Number of resource element used to carry the controlinformation carrying the grant.
 12. The data transmitting deviceaccording to claim 1, wherein at least one of the first resource grantand the second resource grant is received within a dedicated controlinformation signaling from the data receiving node, the dedicatedcontrol information specifying one or more of the modulation and codingscheme, a single subframe or multiple subframes in which resources areallocated, a scheduling delay indicating the location of the allocatesone or more subframes.
 13. A data receiving device for receiving datafrom a data transmitting device over a wireless channel in acommunication system, the data receiving device comprising: granttransmitting circuitry for transmitting a first resource grant for adata transmission in a subframe and a second resource grant for a datatransmission of data in said subframe to the data transmitting device;reception control circuitry for determining according to which of thefirst resource grant and the second resource grant data are to bereceived in the subframe; and a receiver for receiving the data in thesubframe according to the determined first grant or second grant.
 14. Amethod for transmitting data from a data transmitting node to a datareceiving node over a wireless channel in a communication system, themethod comprising: receiving a first resource grant for a datatransmission in a subframe and a second resource grant for a datatransmission of data in said subframe; and selecting according to whichof the first resource grant and the second resource grant data are to betransmitted in the subframe; and transmitting the data in the subframeaccording to the selected first grant or second grant.
 15. A method forreceiving data from a data transmitting device over a wireless channelin a communication system, the method comprising: transmitting a firstresource grant for a data transmission in a subframe and a secondresource grant for a data transmission of data in said subframe to thedata transmitting device; determining according to which of the firstresource grant and the second resource grant data are to be received inthe subframe; and receiving the data in the subframe according to thedetermined first grant or second grant.